A device to device proximity service (Device to Device Proximity Service, D2D ProSe) has become a main topic of study in a 3rd Generation Partnership Project (3rd Generation partnership project, 3GPP) Long Term Evolution (Long Term Evolution, LTE) system.
A communication process of implementing the D2D ProSe service may be referred to as device to device (Device to Device, D2D) communication for short. Currently, when transmitting a D2D signal, a user equipment in D2D communication uses single maximum power for transmission. For example, a user equipment in D2D communication supports transmit power of 23 dBm, and then when transmitting a D2D signal, the user equipment uses the transmit power of 23 dBm for transmission.
In a practical communication process, as shown in FIG. 1A and FIG. 1B, a D2D signal transmitted by a user equipment in D2D communication and an uplink signal transmitted by a user equipment in uplink communication may be multiplexed together in a manner of frequency division multiplexing. FIG. 1A and FIG. 1B are a schematic diagram of a bandwidth of 10 MHz (50 physical resource block pairs (physical resource block pair, PRB Pair)) in a time length of one millisecond. As shown in FIG. 1A and FIG. 1B, in the bandwidth of 10 MHz, there are altogether 50 PRBs, where the first PRB to the Nth PRB and the Mth PRB to the fiftieth PRB are used for transmitting an uplink signal, and the N+1th PRB to the M−1th PRB are used for transmitting a D2D signal.
It can be learned from FIG. 1A and FIG. 1B that, when a D2D signal is transmitted, a subframe format with an extended cyclic prefix (Extended Cyclic Prefix, Extended CP) is used, that is, within a time period of 1 ms, 12 orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) symbols are transmitted; and when an uplink signal is transmitted, a subframe format with a normal cyclic prefix (Normal Cyclic Prefix, Normal CP) is used, that is, within a time period of 1 ms, 14 OFDM symbols are transmitted. The subframe format for transmitting a D2D signal is different from the subframe format for transmitting an uplink signal, and therefore carrier interference exists between the D2D signal and the uplink signal. As shown in FIG. 1A and FIG. 1B, it is assumed that a user equipment 1 is transmitting a D2D signal on PRB#N+1 by using maximum power, and at the same time, a user equipment 2 transmits an uplink signal by using PRB#N. The D2D signal transmitted by the user equipment 1 and the uplink signal transmitted by the user equipment 2 are not aligned in terms of time (the 14 symbols and the 12 symbols cannot be aligned), causing that when receiving the uplink signal transmitted by the user equipment 2 on PRB#N, a network device also receives a leakage signal of the D2D signal transmitted by the user equipment 1, which causes inter-carrier interference. The user equipment 1 uses the maximum power to transmit the D2D signal, and therefore the inter-carrier interference may be very strong, causing accuracy of receiving the uplink signal of the user equipment 2 to reduce.